As for my dream lineup, i'd say make the main stage the big four. Then the side stages can be filled with whatever random crap they fill it with every year. Because let's be honest, if the big four are playing the mainstage no one is gonna give a shit about who else is playing

Main Stage

Metallica
Slayer
Megadeth
Anthrax

Jager stage

Exodus
Lamb of God
Morbid Angel
Deicide
Mayhem

Extreme stage

Cannibal Corpse
Behemoth
Winds of Plague
Dimmu Borgir
Cradle of Filth

im pretty sure that there would be people who cared about the side stage bands i would